Folks,
What techniques would you use for limiting the drag of an element to within
the bounds of another element?
That is, using the code below, the Circle "rateButton" moves very smoothly
all along its' Y axis(it's also contained within a thread for the
UpdateManager runnable queue which is not shown here).
However, it also moves well outside the rectangle rateSlideBase, that is, it
doesn't stop within that rectangle, it moves well beyond the "Y" of the top
of the rectangle and well below the bottom of the rectangle. I previously
used the rectangles "Y" and height attributes to very successfully limit
the rateButton from exceeding the rectangles bounds. But this no longer
works when using the SVGLocatable points and transform matrix, and isn't
useful when the canvas is resized/zoomed, etc...,
if(grab) {
// DOMMouseEvent elementEvent = (DOMMouseEvent) event;
int dragMoveX = dm.getClientX();
int dragMoveY = dm.getClientY();
SVGOMPoint point = new SVGOMPoint(dragMoveX, dragMoveY);
Node node = ((Node) evt.getTarget()).getParentNode();
SVGMatrix Drag_M = ((SVGLocatable) node).getScreenCTM();
Drag_M = Drag_M.inverse();
SVGOMPoint dp = (SVGOMPoint) point.matrixTransform(Drag_M);
Node Base =
(Node)ae.getOwnerDocument().getElementById("rateSlideBase");
//.getParentNode(); // .getAttributeNS(null, "y");
SVGLocatable Base_L = (SVGLocatable)Base;
// Base_L.getBBox;
top = Base_L.getScreenCTM().getB();
hgt = Base_L.getScreenCTM().getD();
rad = Base_L.getScreenCTM().getF();
bot = hgt+top;
top = top+(2*rad);
bot = bot-(2*rad);
newY = dp.getY();
if(newY < top) newY = top;
if(newY > bot) newY = bot;
String cy = String.valueOf(newY);
String setCY = String.valueOf(dp.getY());
ae.getOwnerDocument().getElementById("rateButton").setAttributeNS(null,
"cy",setCY);
I've played around with BBox ( have deleted those attempts out of this
version of the code) but am obviously getting lost in trying to determine
how to get the topmost Y and bottom-most Y of the rectangle to test against.
Thanks for any suggestions,
KWL
